An electromechanical converter converts electrical energy into mechanical energy and vice versa. Electromechanical converters can therefore be used as sensors, actuators and/or generators.
The fundamental structure of such a converter is based on a layer of an electroactive polymer, which is coated on both sides with electrodes. An electroactive polymer is understood as being a polymer which changes its volume and/or its shape in dependence on a voltage applied thereto and/or which is capable of generating a voltage through a change in volume and/or shape.
WO 01/06575 A1 discloses that silicone elastomers, acrylic elastomers, polyurethanes, thermoplastic elastomers, copolymers comprising polytetrafluoroethylene, fluorinated elastomers, and polymers comprising silicone and acrylic groups, for example, can exhibit such electromechanical properties. Unpublished European patent application EP08013648.4 discloses electromechanical converters which are produced from polyisocyanates and/or polyisocyanate prepolymers and diamino-functional compounds. Unpublished European patent application EP08018936.8 discloses electromechanical converters which are produced from solutions of at least one polyurethane in organic solvents. These systems have the disadvantage that, owing to the high content of organic solvents, there are only limited coating possibilities because various demands must be complied with in terms of health and safety, for example in order to protect workers and avoid ignition sources. For ecological reasons too, a system without large amounts of organic solvents is desirable.
Moreover, conventional polymers used in electromechanical converters frequently have disadvantageous properties which may adversely affect the functional capability of the electromechanical converters. These include poor mechanical and other properties, in particular disadvantageous elongation properties, a poor insulating action, in particular low breakthrough field strengths and high electrical conductivities, poor processability and high material costs. In particular, it is not possible to achieve a combination of the desired property features in one material using polymers, for example silicones, that are conventionally employed in electromechanical converters. Even the polyurethanes used in EP08013648.4 and EP08018936.8 to produce the converter exhibit less optimal mechanical properties because the polyurethanes are those having linear polymer chains, which in particular results in less optimal elastomeric properties.